EFFECTS OF CORTISONE ON IN VITRO VIRAL INFECTION. I. INHIBITION OF CYTOPATHOGENESIS BY POLIO, RABIES AND YELLOW FEVER VIRUSES IN HUMAN EMBRYONIC CELLS.

Summary Plaque formation, observation of cytopathic effect, immunofluorescence and mouse inoculation were used variously to evaluate some aspects of cortisone acetate on infection of diploid human embryonic fibroblastic cultures with polio, rabies and yellow fever viruses. Cortisone did not affect poliovirus directly, but did inhibit plaque production when cells were subjected to many passages in its presence. Accumulation of cytopathic effect and spread of virus in cultures infected with rabies virus before serial subculture both were inhibited by cortisone in passage medium. Cortisone exerted a similar cumulative effect on virus production by cells infected with yellow fever virus, and an immediate inhibition of cytopathic response, but both virus production and cytopathic effect returned on removal of cortisone from medium. The findings suggested a cumulative but non-selective effect of cortisone on cellular capacity to respond to virus infection.